It is known that in the presence of a hydrophobic powder, such as a hydrophobic silicon dioxide powder (silicone-coated silica powder), water can be dispersed into fine droplets and enveloped by the hydrophobic material, thus preventing the droplets from rejoining. Such material has been described as “dry water,” “powdered water,” or “powder-to-liquid” and can have a water content of over 95%. It is formed by the intensive mixing of water with hydrophobic material. During this process water droplets are sheathed by the solid particles and prevented from flowing together again. The first experiments on the use of “dry water” as a cosmetic base date from the 1960's. See U.S. Pat. No. 3,393,155. These free-flowing, fine powders liquefy when rubbed on the skin.
More recently, U.S. Pat. No. 6,290,941 describes cosmetic or pharmaceutical powder-to-liquid compositions comprising hydrophobically coated silica particles into which are incorporated water and a water soluble polymer, the composition containing substantially no oil. Such compositions are said to require less silica while retaining the water-holding capacity and permitting substantial elimination of added oil from the formula. The particles can be used with color cosmetics.
WO 2011/075418 discloses a powdery composition comprising a) at least one powder in the form of core-shell particles, the core comprising liquid water or a liquid aqueous phase and the shell comprising hydrophobic or hydrophobized particles, and b) at least one powder comprising carrier, and b1) at least partially water soluble liquid and/or b2) a water reactive substrate each located in and/or on the carrier.
Eshtiaghi et al., Powder Technology, Vol. 223, 2012, pages 65-76 describes a variety of powder-to-liquid materials and proposes mechanisms for their formation. Shell materials used included hydrophobic (silicone-coated) silica, hydrophobic glass beads and polytetrafluoroethylene (PTFE or TEFLON) powder. Core materials included water, glycerol, and polyethylene glycol (PEG). Reported particle sizes for materials containing glycerin were 1200 and 3400 microns.
US 2012/0315312 teaches core-shell particles, the shell of which includes aggregated, hydrophobicized silicon dioxide particles and the core of which includes a liquid phase. The ratio of the silicon dioxide particles to the liquid phase is 2:98 to 40:60 based on the total weight of the particles and 60-100% by weight of glycerol is present in the liquid phase.
U.S. application Ser. No. 13/719,649, filed Dec. 19, 2012 teaches a powder comprising core/shell particles having an average particle size of less than 1000 microns, each particle comprising: 1) a liquid core that is substantially free of water and comprises a polar liquid having a percent surface polarity of at least 24%, and 2) a shell comprising hydrophobic particles. The particles can include an active.
Color cosmetics, such as eye shadow, foundation, blush, concealer and the like are commercially available in powder form. They are used to enhance facial appearance and cover up imperfections. The powder includes inorganic and/or organic pigments. The powder may be applied by brush or pad. It is highly desirable to have skin color cosmetic products not only provide make-up effects (e.g., cover/mask skin infection by colored powder and pigments), but also deliver true benefits to the skin, e.g., moisturization (to prevent facial skin from being flakey and itchy), and removal of excess sebum oil (to prevent blockage of hair follicles or the opening of the sebaceous ducts to cause acne or blackheads). However, it is difficult to provide the benefits of both moisturization and sebum removal from the same color cosmetic product (e.g., a facial foundation powder), since most skin moisturizing agents are oily substances and tend to block skin pores. Over-removing sebum leads to symptoms of dry skin. There is a need for improved color cosmetic compositions.
Applicants have now discovered novel compositions and a method of enhancing the topical application of color cosmetics. The compositions include powder-to-cream particles containing a liquid core and a powder shell. Compositions containing such particles are also convenient to use while providing a cream-like, pleasant skin feel and skin substantivity (the ability to remain on the skin). The compositions can be used in cosmetic, skin care, and other personal care products, as well as in other applications and industries.